opine vs sound off

opine and sound off both are verbs.

Word	Noun	Adjective	Verb	Adverb
opine	No	No	Yes	No
sound off	No	No	Yes	No

As verbs, opine and sound off are synonyms defined as:

opine and sound off: express one's opinion openly and without fear or hesitation

Other synonyms of opine include animadvert, speak out, speak up.

opine (verb)	sound off (verb)
expect, believe, or suppose	express complaints, discontent, displeasure, or unhappiness
express one's opinion openly and without fear or hesitation	express one's opinion openly and without fear or hesitation
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